// 在react17以前，babel转换是老的写法
 const babel = require('@babel/core')
 const sourceCode = `
 <h1>
    hello<span style={{color:'red'}}>world</span>
 </h1>
 `
 const result = babel.transform(sourceCode, {
    plugins: [
        ["@babel/plugin-transform-react-jsx", {runtime: 'classic'}]
    ]
 })
console.log(result.code)

/*#__PURE__*/
React.createElement("h1", null, "hello", /*#__PURE__*/React.createElement("span", {
    style: {
        color: 'red'
      }
}, "world"));